The Metropolitan Police said it was treating the incident as a hate crime.

The Metropolitan Police appealed for witnesses on Saturday after the stabbing of a 17-year-old in Croydon on Friday night (31 March). Investigating officers said they were treating the incident as a hate crime.

The attack by a "large group" left the young man in a critical condition after he was confronted at a bus stop on Shrublands Avenue, which was later revised down to serious but stable on Saturday afternoon. It was thought by police that young man in question was seeking asylum in the UK.

Investigating officer Detective Sergeant Kris Blamires of Croydon CID said: "At this early stage it is believed that about eight suspects approached the victim as he waited at a bus stop with two friends outside the Goat Public House in the Shrublands.

"It is understood that the suspects asked the victim where he was from and when they established that he was an asylum seeker they chased him and launched a brutal attack."

Blamires said the young man sustained "serious head and facial injuries" after receiving repeated blows to the head by his attackers. The victim had been with two male friends who escaped, suffering only minor injuries.

The victim was left unconscious, and a number of people came to his aid, said Blamires. He added: "All communities stand together against hate and we would ask anyone with any information to come forward immediately."

Last year it was revealed that the number of reported hate crimes in the UK had surged since the EU referendum. The National Police Chiefs' Council's figures which were reported last year showed a 49% rise in incidents to 1,863 in the last week of July compared with the same time the previous year. The week after saw a 58% increase in incidents to 1,787.

The increase was thought by some to be linked to the vote, which they said gave rise to some sense of legitimacy in those harbouring far-right sympathies with the Leave campaign often focussed on issues around immigration. The attack on the teenager follows the triggering of Article 50 by Prime Minister Theresa May on Thursday, which officially starts Great Britain's divorce proceedings from the European Union.

The Met said it had increased its number of specialist investigators dealing with hate crime in London by 30% in the last two years. It said it recognised that hate crime was "largely under reported" and encouraged any victims or witnesses of hate crime to get in touch with police quickly.

No arrests had been made in connection with the Croydon attack by Saturday afternoon and Police are urging any witnesses to get in touch by calling police on 101 or anonymously to Crimestoppers on 0800 555 111.

The Metropolitan police has increased the number of officers dedicated to hate crime in the last two years, it saidEddie Keogh/ Reuters